Joining member having ventilation function and joining structure using same

ABSTRACT

A joining member ( 1 ) includes an air-permeable membrane ( 11 ), a first adhesive layer ( 21 ) provided on a side of a first principal surface ( 11   a ) of the air-permeable membrane ( 11 ), a second adhesive layer ( 22 ) provided on a side of a second principal surface ( 11   b ) of the air-permeable membrane ( 11 ), an opening ( 21   h ) formed in the first adhesive layer ( 21 ), and a vent groove ( 1   d ) formed through the second adhesive layer ( 22 ) or between the second adhesive layer ( 22 ) and the air-permeable membrane ( 11 ). The vent groove ( 1   d ) includes a first portion (D 1 ) extending from an outer peripheral edge of the joining member ( 1 ) to a region corresponding to the opening ( 21   h ) and a second portion (D 2 ) to which the second principal surface ( 11   b ) of the air-permeable membrane ( 11 ) is exposed in the region corresponding to the opening ( 21   h ). The vent groove ( 1   d ) provides an air passage ( 1   v ) between a housing ( 31 ) and a support body ( 32 ) to communicate an inside of the housing ( 31 ) and an outside of the housing ( 31 ) when the housing ( 31 ) is fixed to the support body ( 32 ) using the joining member ( 1 ).

TECHNICAL FIELD

The present invention relates to a joining member having a ventilation function and a joining structure including the joining member.

BACKGROUND ART

A housing that requires ventilation is provided with a vent hole for ensuring communication between the inside and outside of the housing for ventilation. In order to prevent foreign substances such as water and dust from entering the housing through the vent hole, a ventilation member is attached to the vent hole. In order to attach the ventilation member to the housing, a double-sided adhesive tape or an adhesive is commonly used (see Patent Literature 1). In the case where the housing is made of a thermoplastic resin, the ventilation member can also be welded to the vent hole of the housing.

In order to fix the above-mentioned housing to a support body, a joining member is used in addition to the above-mentioned ventilation member. Examples of this joining member include double-sided adhesive tapes, adhesives, and screws.

CITATION LIST Patent Literature

Patent Literature 1: JP 2005-070542 A

SUMMARY OF INVENTION Technical Problem

For a conventional configuration, it is necessary to prepare a ventilation member and a joining member separately.

It is an object of the present invention to provide a member having both the function of a ventilation member and the function of a joining member.

Solution to Problem

The present invention provides a sheet-like joining member having a ventilation function and used to fix a housing having a vent hole to a support body. The joining member includes: an air-permeable membrane having a first principal surface and a second principal surface; a first adhesive layer provided on a side of the first principal surface of the air-permeable membrane, the first adhesive layer being adapted to be brought into contact with the housing around the vent hole; an opening formed in the first adhesive layer so that the first principal surface of the air-permeable membrane faces the vent hole of the housing when the first adhesive layer comes into contact with the housing; a second adhesive layer provided on a side of the second principal surface of the air-permeable membrane, the second adhesive layer being adapted to be brought into contact with the support body; and a vent groove formed through the second adhesive layer or between the second adhesive layer and the air-permeable membrane so as to provide an air passage between the housing and the support body to communicate an inside of the housing and an outside of the housing when the housing is fixed to the support body using the joining member, the vent groove including a first portion extending from an outer peripheral edge of the joining member to a region corresponding to the opening and a second portion to which the second principal surface of the air-permeable membrane is exposed in the region corresponding to the opening.

The present invention also provides a joining structure including: a support body; a housing having a vent hole and fixed to the support body; and the above-mentioned joining member disposed between the support body and the housing so as to fix the housing to the support body.

Advantageous Effects of Invention

In the joining member of the present invention, the first adhesive layer is provided on the first principal surface side, and the second adhesive layer is provided on the second principal surface side. The air-permeable membrane is disposed between the first adhesive layer and the second adhesive layer. The first adhesive layer and the second adhesive layer serve to fix the housing to the support body with the air-permeable membrane placed between the housing and the support body. The first adhesive layer adapted to be brought into contact with the housing has an opening formed therein. The vent groove is formed through the second adhesive layer or between the second adhesive layer and the air-permeable membrane so as to provide an air passage between the housing and the support body to communicate the inside of the housing and the outside of the housing. The opening and the vent groove serve to ventilate the housing through the air-permeable membrane.

As described above, the joining member of the present invention has both the joining function and the ventilation function. Therefore, the number of component parts required to produce the joining structure including the housing and the support body can be reduced. The number of man-hours required in the process for producing the joining structure can also be reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a perspective view of a joining structure according to an embodiment of the present invention.

FIG. 1B is a cross-sectional view of the joining structure shown in FIG. 1A.

FIG. 2A is an exploded perspective view of a joining member used in the ventilation structure shown in FIG. 1A.

FIG. 2B is a cross-sectional view of the joining member.

FIG. 3 is a plan view of a first adhesive layer.

FIG. 4 is a plan view of a second adhesive layer.

FIG. 5 is a diagram for explaining the ventilation function of the joining member.

FIG. 6A is an exploded perspective view of a joining member according to a first modification.

FIG. 6B is a cross-sectional view of the joining member according to the first modification.

FIG. 7A is an exploded perspective view of a joining member according to a second modification.

FIG. 7B is a cross-sectional view of the joining member according to the second modification.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1A is a perspective view of a joining structure according to the present embodiment. FIG. 1B is a cross-sectional view taken along a straight line IB-IB in FIG. 1A.

As shown in FIG. 1A and FIG. 1B, a joining structure 30 includes a housing 31, a support body 32, and a joining member 1. The housing 31 has a vent hole 31 h. The joining member 1 is a sheet-like member and has a ventilation function. The joining member 1 is disposed between the housing 31 and the support body 32 and fixes the housing 31 to the support body 32.

FIG. 1A and FIG. 1B show the case where the support body 32 is a solar cell panel and the housing 31 is a terminal box of a solar cell. In FIG. 1A, cables 33 extend from the housing 31.

As shown in FIG. 2A and FIG. 2B, the joining member 1 includes a first adhesive layer 21, a second adhesive layer 22, a third adhesive layer 23, an air-permeable membrane 11, and a spacer 12. The first adhesive layer 21 is provided on the side of a first principal surface 11 a of the air-permeable membrane 11. The second adhesive layer 22 is provided on the side of a second principal surface 11 b (opposite to the first principal surface 11 a) of the air-permeable membrane 11. The spacer 12 is provided between the second adhesive layer 22 and the air-permeable membrane 11. The third adhesive layer 23 is provided between the spacer 12 and the air-permeable membrane 11. That is, in the joining member 1, the first adhesive layer 21, the air-permeable membrane 11, the third adhesive layer 23, the spacer 12, and the second adhesive layer 22 are stacked in this order. More specifically, the first adhesive layer 21 and the air-permeable membrane 11 are in direct contact with each other, the air-permeable membrane 11 and the third adhesive layer 23 are in direct contact with each other, the third adhesive layer 23 and the spacer 12 are in direct contact with each other, and the spacer 12 and the second adhesive layer 22 are in direct contact with each other.

The air-permeable membrane 11 has the properties of preventing water and dust from entering therein and allowing air to pass therethrough. That is, the air-permeable membrane 11 provides the waterproof function, dustproof function, and ventilation function to the joining member 1.

The material of the air-permeable membrane 11 is, for example a porous material. Given that the joining member 1 is sometimes used outdoors and exposed to rain or mud, it is preferable to use, as the air-permeable membrane 11, a membrane including a porous polytetrafluoroethylene (PTFE) membrane having water resistance and stain resistance. The structure of the air-permeable membrane 11 is not particularly limited. For example, the air-permeable membrane 11 may have a net structure or a nonwoven fabric structure. The air-permeable membrane 11 is square in plan view, but it may have another shape such as a polygon other than a square, or a circle.

A porous PTFE membrane can be produced by the following method, for example. First, a liquid lubricant is added to a PTFE fine powder to preform a pasty mixture. The liquid lubricant is not particularly limited as long as it can wet the surface of the PTFE fine powder and can be removed by extraction or heating. Hydrocarbons such as liquid paraffin, naphtha, and white oil can be used as the liquid lubricant. The appropriate amount of the liquid lubricant added is about 5 to 50 parts by weight per 100 parts by weight of the PTFE fine powder. The above-mentioned preforming is performed at such a pressure that the liquid lubricant is not squeezed out. Next, the mixture obtained by the above-described preforming is formed into a sheet by paste extrusion or rolling to obtain a PTFE sheet. Next, this PTFE sheet is stretched uniaxially or biaxially. Thus, a porous PTFE membrane is obtained. Stretching conditions may be determined as appropriate. For example, the temperature for stretching is 30° C. to 400° C., and the stretch ratio is 1.5 to 200 for each stretching direction. In addition, in the case where the porous PTFE membrane is not sintered in the stretching process, it is preferable to sinter the porous PTFE membrane at a temperature equal to or higher than the melting point of the porous PTFE membrane after the stretching.

The air-permeable membrane 11 may include an air-permeable membrane body that prevents water and dust from entering therein and allows air to pass therethrough and a reinforcing member for reinforcing the air-permeable membrane body. Examples of the air-permeable membrane body includes membranes made of the porous materials described above. Examples of the material of the reinforcing member include synthetic fibers made of resins such as polyolefins (e.g., polyethylene and polypropylene), polyamides, polyesters, aromatic polyamides, acrylics, and polyimides, and composite materials of these. Preferably, the reinforcing member has a structure whose permeability can be easily increased, such as a nonwoven fabric, a woven fabric, a net, or the like. The arrangement of the air-permeable membrane body and the reinforcing member is not particularly limited. For example, the reinforcing member may cover one side of the air-permeable membrane body, or the reinforcing members may cover both sides of the air-permeable membrane body. From the viewpoint of ensuring the waterproofness of the housing 31, it is preferable to arrange the air-permeable membrane body and the reinforcing member so that the air-permeable membrane body comes into direct contact with the first adhesive layer 21. In view of this point, the reinforcing member preferably covers only one side of the air-permeable membrane body.

The thickness of the air-permeable membrane 11 is, for example, 5 to 2000 μm, and preferably 10 to 500 μm.

Preferably, the air-permeable membrane 11 has a water entry pressure of 5 cm/H₂O or more for the following reasons. The internal pressure of the housing 31 is lower than the external pressure thereof in some environments of use. In such a case, even if the air-permeable membrane 11 has water resistance, water or the like outside the housing 31 may penetrate the air-permeable membrane 11 and be drawn into the housing 31. Therefore, it is preferable that the air-permeable membrane 11 have not only water resistance but also a predetermined level of water entry pressure. When the air-permeable membrane 11 has a water entry pressure in the range given above, the risk that outside water or the like may be drawn into the housing can be reduced effectively. This means that, when the air-permeable membrane 11 has a water entry pressure given above, it can have good internal pressure controllability.

The air-permeable membrane 11 may be subjected to oil-repellent treatment. For example, when the housing 31 is used to contain automotive electronic components, window washer fluid, oil such as engine oil and brake oil, etc. may adhere to the vicinity of the housing 31, which in turn adheres to the surface of the air-permeable membrane 11. Oil-repellent treatment makes it possible to more effectively prevent a low surface tension liquid from penetrating the air-permeable membrane 11.

The first adhesive layer 21 is a layer adapted to be brought into contact with the housing 31 around the vent hole 31 h. The first adhesive layer 21 may be made of a single material, or may contain two or more materials. For example, the first adhesive layer 21 may consist only of an adhesive, or may be a double-sided adhesive tape including a substrate and an adhesive applied to both sides of the substrate. From the viewpoint of ease of producing the joining member 1, the first adhesive layer 21 is preferably a double-sided adhesive tape. The same applies to the second adhesive layer 22 and the third adhesive layer 23 as well. In the present embodiment, the first adhesive layer 21 is a double-sided adhesive tape. The thickness of the first adhesive layer 21 is, for example, 25 to 3000 μm.

The second adhesive layer 22 is a layer adapted to be brought into contact with the support body 32. The third adhesive layer 23 is a layer for bonding the spacer 12 to the air-permeable membrane 11. The second adhesive layer 22 and the third adhesive layer 23 can each have the same structure as the first adhesive layer 21. In the present embodiment, the second adhesive layer 22 and the third adhesive layer 23 are each a double-sided adhesive tape.

The spacer 12 is a member for maintaining a space between the air-permeable membrane 11 and the support body 32. In the present embodiment, a polyethylene terephthalate (PET) film is used as the spacer 12. Another plastic film may be used as the spacer 12.

In the joining structure 30, the joining member 1 forms an air passage communicating the inside and outside of the housing 31. In the present embodiment, the air-permeable membrane 11 is sandwiched between the first adhesive layer 21 and the second adhesive layer 22, the spacer 12 and the third adhesive layer 23, so as to form the air passage. The shapes of the first adhesive layer 21, the second adhesive layer 22, the spacer 12, and the third adhesive layer 23 for forming the air passage, and that air passage are described below.

FIG. 3 is a plan view of the first adhesive layer 21. As shown in FIG. 3, the first adhesive layer 21 has an opening 21 h formed therein. The opening 21 h is provided in the center of the first adhesive layer 21. In the ventilation structure 30, the opening 21 h of the first adhesive layer 21 coincides with the vent hole 31 h of the housing 31.

FIG. 4 is a plan view of the second adhesive layer 22. As shown in FIG. 4, the second adhesive layer 22 has a vent recess 22 d formed therein.

In the present embodiment, the spacer 12 and the third adhesive layer 23 have the same shape as the second adhesive layer 22 in plan view. That is, the spacer 12 has a vent recess 12 d, and the third adhesive layer 23 has a vent recess 23 d. The vent recess 12 d and the vent recess 23 d have the same shape as the vent recess 22 d in plan view.

In the joining member 1 of the present embodiment, the second adhesive layer 22, the spacer 12, and the third adhesive layer 23 are stacked so that their side edges are aligned (see FIG. 2B). Thus, the second adhesive layer 22, the spacer 12, and the third adhesive layer 23 form a vent groove 1 d having a thickness corresponding to the total thickness of these three layers.

In other words, the vent groove 1 d is formed through the second adhesive layer 22, the spacer 12, and the third adhesive layer 23. The vent groove 1 d includes a first portion D1 and a second portion D2. The first portion D1 of the vent groove 1 d is a portion extending from the outer peripheral edge of the joining member 1 to a region corresponding to the opening 21 h (a region overlapping or coinciding with the opening 21 h in plan view). The second portion D2 of the vent groove 1 d is a portion to which the second principal surface 11 b of the air-permeable membrane 11 is exposed in the region corresponding to the opening 21 h. The vent groove 1 d is separated from the opening 21 h by the air-permeable membrane 11. As described below, when the housing 31 is fixed to the support body 32 using the joining member 1, the vent groove 1 d provides an air passage between the housing 31 and the support body 32 to communicate the inside of the housing 31 and the outside of the housing 31.

Next, the ventilation function of the joining member 1 is described with reference to FIG. 5. FIG. 5 is a cross-sectional view taken along a straight line V-V in FIG. 1A. As shown in FIG. 5, since the opening 21 h is formed in the first adhesive layer 21, the first principal surface 11 a of the air-permeable membrane 11 faces the vent hole 31 h of the housing 31 when the first adhesive layer 21 comes into contact with the housing 31. Therefore, the interior space of the housing 31, the vent hole 31 h, and the opening 21 h communicate with each other. On the other hand, the vent groove 1 d is formed between the support body 32 and the air-permeable membrane 11 and communicates with the exterior space of the housing 31. More specifically, a space of the vent groove 1 d is formed between the support body 32 and the air-permeable membrane 11, and this space and the exterior space of the housing 31 communicate with each other. That is, in the joining structure 30, the interior space and the exterior space of the housing 31 are separated from each other only by the air-permeable membrane 11. This means that the opening 21 h, the air-permeable membrane 11, and the vent groove 1 d form an air passage 1 v. The air passage 1 v is never blocked by the support body 32. Therefore, the air passage 1 v ensures communication between the interior space and the exterior space of the housing 31 for good ventilation of the housing 31.

In the present embodiment, the vent groove 1 d is also formed through the spacer 12, and has a depth equal to or greater than the thickness of the spacer 12. The bottom of the vent groove 1 d is formed of the second principal surface 11 b of the air-permeable membrane 11. The vent groove 1 d has a depth equal to the total thickness of the second adhesive layer 22, the spacer 12, and the third adhesive layer 23. As described later, the spacer 12 and the third adhesive layer 23 are not essential components. However, the presence of the spacer 12 and the third adhesive layer 23 makes the vent groove 1 d deeper. That is, when the joining structure 30 is assembled, the air flow cross sectional area of the air passage 1 v is increased on the side of the second principal surface 11 b of the air-permeable membrane 11. As a result, good ventilation of the housing 31 can be ensured in the joining structure 30.

The dimensions of the vent groove 1 d is not particularly limited, but the depth of the vent groove 1 d is, for example, 50 to 5000 μm, and preferably 200 to 300 μm.

The width of the vent groove 1 d is preferably 1 to 20 mm in plan view in order to achieve both the air flow cross sectional area large enough for the vent groove 1 d and the strength high enough for the joining member 1.

In the present embodiment, the vent groove 1 d is a recess having a combined shape of a semicircle and a rectangle in plan view. However, the shape of the vent groove 1 d is not limited. For example, the vent groove 1 d may be a recess having a quadrangular shape such as a rectangle in plan view. The second adhesive layer 22, the spacer 12, and the third adhesive layer 23 may each be divided into two or more regions so that the vent groove 1 d has a cross shape or the like in plan view.

In the joining member 1, the vent recess 22 d, the vent recess 12 d, and the vent recess 23 d completely coincide with each other. However, the side edges of the vent recesses 22 d, 12 d and 23 d may be slightly misaligned with each other as long as the vent groove 1 d having a depth equal to the total thickness of the second adhesive layer 22, the spacer 12, and the third adhesive layer 23 is formed.

In the ventilation structure 30 of the present embodiment, the position of the joining member 1 and the position of the housing 31 are determined so that the vent groove 1 d extends in a depression angle direction. This configuration makes it possible to prevent a liquid such as water from remaining in the vent groove 1 d, resulting in a decrease in the possibility that the liquid may enter the housing 31 from the outside. However, the direction in which the vent groove 1 d opens is not limited, and the vent groove 1 d may extend in an elevation angle direction.

The diameter of the opening 21 h formed in the first adhesive layer 21 is not particularly limited, and it is 2 to 50 mm, for example. In the present embodiment, the opening 21 h has a circular shape, but it may have another shape, for example, a quadrangular shape.

The positional relationship between the vent hole 31 h and the opening 21 h is not particularly limited, but preferably the centers thereof coincide with each other. Thereby, good ventilation of the housing 31 can be ensured. In the present embodiment, the vent hole 31 h has the same shape as the opening 21 h, but they need not necessarily have the same shape. Their shapes may be slightly different from each other.

(First Modification)

A joining member 101 shown in FIG. 6A and FIG. 6B has a second adhesive layer 122 instead of the second adhesive layer 22 of the joining member 1 in the embodiment described above. That is, in the joining member 101, the first adhesive layer 21, the air-permeable membrane 11, the third adhesive layer 23, the spacer 12, and the second adhesive layer 122 are stacked in this order. The first adhesive layer 21 and the air-permeable membrane 11 are in direct contact with each other, the air-permeable membrane 11 and the third adhesive layer 23 are in direct contact with each other, the third adhesive layer 23 and the spacer 12 are in direct contact with each other, and the spacer 12 and the second adhesive layer 122 are in direct contact with each other. The second adhesive layer 122 does not have a vent recess like the vent recess 22 d. That is, the second adhesive layer 122 has the same shape as the air-permeable membrane 11 in plan view. The second adhesive layer 122 is an adhesive layer having the same structure as the second adhesive layer 22 except for this point. In the first modification using this configuration, a vent groove 101 d is formed through the spacer 12 and the third adhesive layer 23 located between the second adhesive layer 122 and the air-permeable membrane 11. The vent groove 101 d is covered by the second adhesive layer 122 in the thickness direction of the second adhesive layer 122.

In a joining structure (not shown) including the joining member 101, the bonding area between the joining member 101 and the support body 32 (i.e., the contact area between the second adhesive layer 122 and the support body 32) can be made larger than the bonding area between the joining member 1 and the support body 32 (i.e., the contact area between the second adhesive layer 22 and the support body 32). Therefore, the housing 31 can be fixed to the support body 32 more firmly when the joining member 101 is used than when the joining member 1 is used.

In the first modification, the second adhesive layer 122 does not serve as an air passage. Therefore, in the first modification, the total thickness of the spacer 12 and the third adhesive layer 23 is preferably greater than that in the embodiment described above. That is, it is preferable that the total depth of the vent recess 12 d and the vent recess 23 d be greater than that in the embodiment described above. For this reason, in the first modification, the total thickness of the spacer 12 and the third adhesive layer 23 is preferably 200 to 300 μm.

(Second Modification)

A joining member 201 shown in FIG. 7A and FIG. 7B does not have the spacer 12 and the third adhesive layer 23 of the joining member 1 in the embodiment described above. That is, in the joining member 201, the first adhesive layer 21, the air-permeable membrane 11, and the second adhesive layer 22 are stacked in this order. The first adhesive layer 21 and the air-permeable membrane 11 are in direct contact with each other, and the air-permeable membrane 11 and the second adhesive layer 22 are in direct contact with each other. In the second modification, a vent groove 201 d is formed through the second adhesive layer so that the vent groove 201 d has a depth equal to the thickness of the second adhesive layer 22, and the bottom of the vent groove 201 d is formed of the second principal surface 11 b of the air-permeable membrane 11. That is, in the second modification, the vent groove 201 d is a vent recess 22 d formed in the second adhesive layer 22.

The configuration of the joining member 201 is simpler than that of the joining member 1. Therefore, the joining member 201 is superior to the joining member 1 in terms of the material costs and ease of production.

However, the joining member 201 does not have layers corresponding to the spacer 12 and the third adhesive layer 23 in the embodiment described above. That is, the joining member 201 does not have the vent recess 12 d and the vent recess 23 d. Therefore, in the second modification, it is preferable that the thickness of the second adhesive layer 22 be greater than that in the embodiment described above. That is, the depth of the vent recess 22 d is preferably greater than that in the embodiment described above. For this reason, in the second modification, the thickness of the second adhesive layer 22 is preferably 200 to 300 μm.

Examples

Hereinafter, the present invention will be described more specifically by way of an actually produced joining member. The present invention is not limited to these examples.

(Preparation of Component Parts)

First, component parts of the joining member were prepared.

A porous PTFE membrane was produced in the following manner. First, a pasty mixture obtained by adding 19 parts by weight of a liquid lubricant (normal decane) per 100 parts by weight of PTFE fine powder (trade name F104, manufactured by Daikin Industries, Ltd.) was preformed, and the resulting preformed body was formed into a round bar form by paste extrusion to obtain a formed body. Next, the formed body was rolled into a sheet with a thickness of 0.2 mm. After the rolling, the liquid lubricant was removed from the sheet in a drying furnace at 150° C. Next, the sheet was stretched in the longitudinal direction at a stretch ratio of 2 at 280° C., and further stretched at a stretch ratio of 4 at a temperature of 360° C. After the stretching in the longitudinal direction, the sheet was stretched in the transverse direction at a stretch ratio of 5 in a 100° C. atmosphere. Thus, a porous PTFE membrane was obtained. The thickness of the porous PTFE membrane thus obtained was 80 μm.

A double-sided tape (No. 5620A, manufactured by Nitto Denko Corporation) was prepared for use as a first adhesive layer, a second adhesive layer, and a third adhesive layer. The thickness of this double-sided take was 200 μm.

As a spacer, a PET film (Lumirror S10 (#100) manufactured by Toray Industries, Inc.) was prepared. The thickness of this PET film was 100 nm.

(Shaping of Component Parts)

Next, the component parts thus prepared were subjected to shaping to adjust the dimensions and shapes thereof. Specifically, each of the component parts was subjected to punching using a Thomson die cutter.

First, the porous PTFE membrane was punched into a square of 50 mm×50 mm in plan view.

Next, the both-sided adhesive tape for the first adhesive layer was punched into a shape as shown in FIG. 3. Specifically, the both-sided adhesive tape was punched out so that the resulting first adhesive layer had a square outline of 50 mm×50 mm in plan view and had a 10-mm-diameter circular hole formed in the center of the layer.

Next, the both-sided adhesive tape for the second adhesive layer was punched into a shape as shown in FIG. 4. Specifically, the both-sided adhesive tape was punched out so that the resulting second adhesive layer had unrecessed three sides of 50 mm and one recessed side and that the recess included a 10-mm-diameter circular region formed in the center of the layer (i.e., a region coinciding with the hole of the first adhesive layer when the joining member was assembled) in plan view. Next, the both-sided adhesive layer for the third adhesive layer was punched in the same manner as in the formation of the second adhesive layer. Next, the PET film was punched in the same manner as in the formation of the second adhesive layer.

(Stacking of Component Parts)

The materials obtained by punching as described above were stacked as shown in FIG. 2B. Thus, the joining member was produced. The thickness of the joining member was 780 μm.

[Evaluation of Ventilation Performance]

The ventilation performance of the joining member thus produced was evaluated in the following manner.

First, an aluminum plate and an aluminum box having a circular vent hole with a diameter of 8 mm and a suction port to which a pump could be connected were prepared. Next, the joining member was placed between the aluminum plate and the aluminum box so as to fix the aluminum box to the aluminum plate. Specifically, the aluminum box and the first adhesive layer of the joining member were brought into contact with each other so that the center of the vent hole of the aluminum box coincided with the center of the hole of the first adhesive layer, and the aluminum plate and the third adhesive layer of the joining member were brought into contact with each other. Thus, the aluminum box was fixed to the aluminum plate. The pump was attached to the suction port of the aluminum box to suck the air out of the aluminum box. The difference between the pressure inside the aluminum box and the pressure outside the aluminum box, and the rate of air flow were measured. The pressure difference was 0.125 kPa, and the rate of air flow was 0.16 cm³/cm²/sec. The measurement results revealed that the produced joining member had good ventilation function.

INDUSTRIAL APPLICABILITY

The joining member of the present invention can be used to fix a terminal box of a solar cell that requires ventilation to a solar cell panel. However, the use of the joining member of the present invention is not limited. For example, the joining member of the present invention can be used to mount an ECU box to a support body such as a car body. 

1. A sheet-like joining member having a ventilation function and used to fix a housing having a vent hole to a support body, the joining member comprising: an air-permeable membrane having a first principal surface and a second principal surface; a first adhesive layer provided on a side of the first principal surface of the air-permeable membrane, the first adhesive layer being adapted to be brought into contact with the housing around the vent hole; an opening formed in the first adhesive layer so that the first principal surface of the air-permeable membrane faces the vent hole of the housing when the first adhesive layer comes into contact with the housing; a second adhesive layer provided on a side of the second principal surface of the air-permeable membrane, the second adhesive layer being adapted to be brought into contact with the support body; and a vent groove formed through the second adhesive layer or between the second adhesive layer and the air-permeable membrane so as to provide an air passage between the housing and the support body to communicate an inside of the housing and an outside of the housing when the housing is fixed to the support body using the joining member, the vent groove including a first portion extending from an outer peripheral edge of the joining member to a region corresponding to the opening and a second portion to which the second principal surface of the air-permeable membrane is exposed in the region corresponding to the opening.
 2. The joining member according to claim 1, further comprising: a spacer provided between the second adhesive layer and the air-permeable membrane; and a third adhesive layer provided between the spacer and the air-permeable membrane, wherein the vent groove is formed at least through the spacer so that the vent groove has a depth equal to or greater than a thickness of the spacer.
 3. The joining member according to claim 2, wherein the vent groove is formed through the second adhesive layer, the spacer, and the third adhesive layer so that the vent groove has a depth equal to a total thickness of the second adhesive layer, the spacer, and the third adhesive layer, and the vent groove has a bottom formed of the second principal surface of the air-permeable membrane.
 4. The joining member according to claim 1, wherein the vent groove is formed through the second adhesive layer so that the vent groove has a depth equal to a thickness of the second adhesive layer, and the vent groove has a bottom formed of the second principal surface of the air-permeable membrane.
 5. The joining member according to claim 1, wherein the air-permeable membrane comprises a porous polytetrafluoroethylene membrane.
 6. The joining member according to claim 1, wherein the first adhesive layer and the second adhesive layer are each formed of a double-sided adhesive tape.
 7. A joining structure comprising: a support body; a housing having a vent hole and fixed to the support body; and a sheet-like joining member disposed between the support body and the housing so as to fix the housing to the support body, wherein the joining member comprises: an air-permeable membrane having a first principal surface and a second principal surface; a first adhesive layer provided on a side of the first principal surface of the air-permeable membrane, the first adhesive layer being in contact with the housing around the vent hole; an opening formed in the first adhesive layer so that the first principal surface of the air-permeable membrane faces the vent hole of the housing; a second adhesive layer provided on a side of the second principal surface of the air-permeable membrane, the second adhesive layer being in contact with the support body; and a vent groove formed through the second adhesive layer or between the second adhesive layer and the air-permeable membrane so as to provide an air passage between the housing and the support body to communicate an inside of the housing and an outside of the housing, the vent groove including a first portion extending from an outer peripheral edge of the joining member to a region corresponding to the opening and a second portion to which the second principal surface of the air-permeable membrane is exposed in the region corresponding to the opening.
 8. The joining structure according to claim 7, wherein the support body is a solar cell panel, and the housing is a terminal box of a solar cell. 